The erosion of sediment from shorelines and waterways is a longstanding problem common to beaches, lakeshore, riverbanks as well as canals and other artificial waterways. Wave action, currents and tides all tend to wear away and destroy shorelines. This destruction occurs either gradually, over long periods of time or suddenly as in the event of a strong storm or hurricane.
In view of the destructive effects such erosion has upon property values as well as public construction projects, a variety of approaches have been developed over the years to preserve shorelines and reduce the effects of erosion. Piers, jetties and breakwalls have all been employed in varying extents and with limited success.
When dealing with sloping banks and shorelines, revetment is a commonly used means for protection. The type of revetment used can vary from simply positioning closely laid stone or boulders along the bank to a more permanent and complex approach including the placement of prefabricated steel or concrete units along the shoreline.
More recently, revetment networks have been developed which provide a number of uniquely designed and similarly sized units or bodies of prefabricated concrete or other heavy material. The units are transported to a jobsite and placed in an interconnected manner to form a matrix network having enhanced cohesion and resistance to wave action.
Typical of such devices is U.S. Pat. No. 4,083,190 (Pey) which discloses a breakwater composed of a network of interconnected elements all of which have a similar size and configuration. Each element consists of a triangular or circular body with three posts extending from the body so that when plural bodies are arranged in layers, the posts interlink within the open portions of adjacent bodies to form a connected, protected network.
The prior art devices and in particular the unit as taught by the Pey patent fail to provide effective shoreline protection in a number of respects. The unit contains sharp corners, edges as well as projecting legs which make it more susceptible to breakage. In addition, the interlock arrangement provided by these units is rather loose fitting, relying upon posts to interfit oversized openings of the adjacent units. If a single post is broken the integrity and strength of the entire network is reduced. Further, units containing posts or legs have a relatively high center of gravity making them less stable and more prone to displacement by wave action or currents. The prior art revetment units are relatively complicated in design, making them expensive to manufacture.
Thus, a need has existed in the art for providing a revetment unit which is of a simple construction yet provides increased interlocking capabilities and enhanced resistance to wave action or currents.